Tension regulator for electrical transmission of speech



No. 609,877. Patented Aug. 30, I898.

- A. .c. COUSENS.

TENSION REGULATOR FOR ELECTRICAL TRANSMISSION OF SPEECH.

(Application fllsd June 15, 1895.)

(No Model.)

Witnesses: Inner 2hr: mima. W

m: MORRIS Pzrzns c0. Puoro'umou WASHINGTON, o c.

NITED STATES PATENT OFFICE.

ALFRED o. OOUSENS, or NEWARK, NEW JERSEY, ASSIGNOR or ONE-HALF TO GEORGE W. OI'IUSETTS.

GREGORY AND JOHN C. EDWARDS, OF BOSTON, MASSA- TENSION-REGULATOR FOR ELECTRICAL TRANSMISSION OF SPEECH.

SPECIFICATION forming part of Letters Patent No. 609,877, dated August 30, 1898. Application filed June 15, 1895.j Serial No. 552,896. (No model.)

To all whom it may concern.-

Be it known that I, ALFRED G. OoUsENs, a citizen of the Kingdom of Great Britain and Ireland, residing at the city of Newark, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Variable-Resistance Mediums; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being bad to the accompanying drawing, and to letters of reference marked thereon, which forms a part of this specifica-' tion.

My invention relates to that class of transmittingtelephones which operate by variations of resistance in an electric circuit, such variations being produced by and conforming to the sound-waves which are to be reproduced at the receiving end of the line. i

As far as I am aware in instruments hitherto constructed the variable-resistance medium consists of substances in a solid, a liquid, or a plastic'state or in combinations of such difierent conditions of matter, a variation of resistance in the circuit resulting from and being directly cognate to a variation of pressure or in intimacy of contact in the case of solids and inchange in length of circuit, depth of immersion, or some other mechanical action upon or in relation to matter in a moist, a liquid, or a plastic state.

I have discovered that the necessary modifications of the electric current for the reproductions of sound-vibrations can be accomplished by chemical or molecular action or disturbance in an inclosed or confined conducting gas or vapor interposed between electrodes normally separated by such gas, the variations in resistance depending principally upon the fact that chemical change is a con- (lition of electrical conductivity in most, if not all, gases, as well as in most liquids, and, conversely, that chemical change or an increase or a decrease in the velocity of chemical change produced by some external force while a current is passing through such gas will produce a corresponding variation in the strength of the current.

Among the practical advantages of this improvement in the art are great clearness of articulation, volume of sound, and extreme sensitiveness. The velocity with whichchemical change or other disturbance is propagated in a gaseous medium makes such a change determined in one part of a system of considerable extent practically instantaneous in all parts of the system. Variations in current strength due to such action are therefore sharp and well defined, and as there is practically no inertia to overcome less force is required to produce a given variation by such means than by any other. 7

In the accompanying drawing a sectional view is shown of a simple and convenient form of transmitter adapted to the practice of my method, the details being restricted as far as possible to such parts as are directly related to the transmitting element proper.

A resonator or sound-receiving diaphragm A, of thin wood or equivalent material, is secured at its periphery by the annular twopart frame 13. A circular opening in the middle of the diphragm A is closed on one side by the front electrode D and on the other side by the electrode F and flexible disk g, forming a closed chamber a for the preferably dry finely-divided material 0 and a conducting gas or vapor derived from said material forming a gaseous variable-resistance medium. The flexible disk 9 is secured to the rear surface of A by the clamping-ring H and supports the electrode F slightly within the rear opening of the chamber 6. The flexible disk g may be of mica, thin sheet metal, or other suitable material. If a conductor, care must be taken to insulate it from H by any known or suitable method.

' The front electrode D, of greater radius than the chamber 6, is rigidly secured at or near its edge to the front of the diaphragm by bolts K, extending through A and the ring H. The terminal wires of atelephone-circuit L and M are respectively connected to the in the closed chamber c, said preferably finelydivided material being under transmitting conditions separated from the electrode F by a stratum of the gas, the depth or thickness of the stratum depending upon the nature of the material between the electrodes, the heating effect of the current, and upon the amplitude of the movements of F relatively to A. I have not attempted to show such a stratum of gas in the drawing, because any graphic representation thereof might be misleading, as the layer of gas need be of very slight depth. The electrodes D and F are of any suitable conducting material.

As the transmission of speech depends, primarily, upon the formation at high temperatures of a conducting-gas and the approximating surfaces of the electrodes or particles are most strongly heated by the passage of the current, they will necessarily be separated by a stratum of the gas so formed, and the greater the separation, other things being .the electrode.

equal, the greater will be the volume of sound resulting from the greater thickness of the layer of gas between the electrodes and the particles, and therefore the greater possible variation in the resistance of the circuit, resulting from a chemical change or disturbance inthe stratum and the difference in electrical conductivity produced thereby.

If the material in the, chamber is dry and finely divided and becomes packed together or against the'electrodes, the mechanical force exerted by the vapor tension of the gas formed between the approximating surfaces will not be great enough to produce the separation between them required to give the best possible results. The disk g, supporting the back electrode, must therefore be flexible enough to permit of a slight movement of the electrode relatively to the diaphragm through the difference in their inertia or fundamental rate of vibration, the vibrations of the electrodes resulting from movements of the air in contact with the diaphragms which are indirectly imparted to the back electrode through the intermediary of the flexible disk supporting Such movements, while not bearing upon the essential action of the transmitter, tend to force the preferably finely-divided material in the chamber away from the position occupied by the electrode when at rest, thus making way for a layer of gas of the required depth, which then forms part of the circuit, the inertia of the particles causing them to remain more or less constantly in the position into which they are forced by the electrode, the movements of the electrode being of such a nature as to render the average distance between the particles and the electrodes, and therefore the resistance of the circuit as far as such movements are concerned, practically constant.

The contents of the closed chamber in the transmitter in my invention are dry and in either a solid or gaseous state. While this is a simple and efiective means for maintaining a gaseous stratum of the required depth between the finely-divided material and one of the electrodes, I do not limit myself to this particular device for accomplishing the purpose, as the same result can be obtained by various other means.

The metallic compound which I preferably employ when the same is to be used in a state of fine division consists, essentially, of titanium, aluminium, and potassium,formed by heating together to a high temperature in a closed crucible protected from the action of the air a salt of titanium and metallic aluminium and potassium in the required proportions. The precise nature of the material employed will depend upon the conditions under which it is to be usedthat is to say, upon the quantity and pressure of the current,the mechanical construction of the transmitter, whether a homogeneous or a granular material is required, and the specific gravity and electrical conductivity of the material which under the different conditions of use will give the best results. I have obtained the best results with a combination of elements the respective atomic weights of which or the multiple thereof is divisible by twelve, combined in such proportions that the relative differences in such weights are equal to twelve, as in the case of a compound of titanium, aluminium, and potassium, represented by the formula This compound or alloy, although volatilizable, is infusible, or nearly so.

The properties of many compounds appear to be functions of the difference in the atomic weights of the elements composing the compound. I have observed, for instance, that a liquid condition or a low melting-point appears to be determined by a difference of about seven or some multiple of seven, as in the case of the normally fluid alloynformed by combining two atoms of sodium with one atom of potassium, and the properties of water and the low melting-point of a number of other atomic compounds in which such a relation exists also indicate the existence of such a law. Other properties appear to be determined by other differences; but the law is too complicated by a number of different factors to be used for the purpose of comprehensively classifying all the combinations of elements which may be used for telephonic purposes, but serves to explain the fact that certain alloys are more volatile than fusible and also explains the action of some gaseous elements in determining or facilitating the volatilization of some otherwise refractory elements without, as far as known, in some cases combining therewith. The distance to which electrodes of some compounds can be moved away from each other without breaking the circuit, and in a corresponding manner the volume of sound obtained being determined to some extent by the presence of certain gaseous elements-nitrogen or hydrogen, for instancewhen such elements are present in the free state, and the effects so produced or resulting from the action of the assumed law are to be understood as included under the general term chemical action.

Under transmitting conditions the gaseous stratum between the electrodes may be regarded as a field in which two tendencies are at work on the one hand a source of energy from without the system tending to produce decomposition of the gas and on the other hand the chemical force or affinity of the component parts of the system tending to produce recombination, a condition of mobile equilibrium being attained when the amount of decomposition and recombination per unit of time is the same, variations in the resistance of the circuit corresponding to soundwaves resulting principally from the rate of chemicalchange determined in the system in one direction by the action of molecular disturbances produced in the gas by soundwaves through the intermediary of the diaphragm, the same gas under different conditions or different gases under the same conditions being either an insulator and requiring the electromotive force intensity of the current to exceed a certain value before any electricity at all will pass through it or a conductor and unable to insulate a difference of potential of one one-thousandth of a volt, the best conducting-gases when not being those which are most easily decomposed when strongly heated and are therefore undergoing chemical change. That chemical change may be determined in a gas by sound-waves is proved by the fact that acetylene, cyanogen, nitrous and nitric oxid,the oxids of chlorin and other gases may be decomposed by the direct action of vibrations produced by a loud sound or note. The amount of chemical change produced in the system by molecular disturbances will depend upon the force and amplitude of the sound-vibrations and upon the normal affinity of the elements composing the system, the action of sound-waves being in some respects analogous to the chemical action of light-waves, the shrillest sounds being comparable to the ultra-violet waves. The precise nature of the reactions recurring in the system will depend upon the. gases present and the quantity and pressure of the current employed. With an alloy consisting of titanium, aluminium, and potassium two or more compound gases consisting of two or more of these elements and free potassiumvapor are formed by the action of the current. Potassium-vapor is the best known conducting-gas of an elementary character, but offers more resistance to the passage of -the current than when forming a compound gas with titanium and aluminium, variation in the resistance of the circuit corresponding to sound-waves depending, as aforesaid, upon the relative proportions or different conditions of gaseous matter present at any given time and upon the change or rate of change from one to the other determined by the action of sound-waves.

Having fully described my invention, what I claim, and desire to secure by Letters Patent, is-

1. The herein-described method of transmitting sound, which consists in subjecting to the action of the transmitting-current a substance from which is thereby generated a gaseous variable-resistance medium, and varying the resistance of said gaseous medium by the action of and to conform to the sound waves to be transmitted.

2. The herein-described method of transmitting sound, which consists in passing the transmitting-current through a plurality of electrodes in a closed chamber and composed of a conducting substance from which is generated a variable-resistance medium on the passage of the transmitting-current, and varying the resistance of such gaseous medium by the action of and in conformity with the sound waves to be transmitted.

3. In a transmitting-telephone, a diaphragm or sound-board, an electrode'rigidly secured thereto and forming the front wall of a resistance-chamber supported by said diaphragm, a spacingelectrode supported within the rear opening of the chamber by a flexible disk secured to the side wall or casing of said chamber, and together with the said electrode forming a wall thereof, and a conducting substance in said chamber capable of generating a gaseous variable-resistance medium on the passage of the transmitting-current, in series with and separating the electrodes, the resistance of said gaseous medium being varied by the action of and in conformity with the soundwaves to be transmitted, substantially as described.

4. In a transmitting-telephone, the combination of a sound-receiving diaphragm, an electrode rigidly secured to said diaphragm and forming the front wall of a resistancechamber situated approximately in the middle of said diaphragm and between the planes of the two surfaces thereof; a spacing-electrode supported within the rear opening of said chamber, a flexible disk to which said spacing-electrode is secured, clamped to the back of said diaphragm; and finely-divided conducting material in a loose and free state within said chamber, a space between said finely-divided material and said back electrode produced by movements of said electrode being normally occupied by a stratum of gas or gases derived entirely or in part from said finely-divided material and constituting the variable-resistance medium within the said chamber.

5. The combination of a sound-receiving diaphragm of thin wood; a chamber approximately situated between the planes of the surfaces of the said diaphragm, the front opening of said chamber closed by a plate of greater radius rigidly secured at or near its edge to tween the approximating surfaces thereof and normally separated by said gas and in series therewith, said gas constituting the variable-resistance medium of a transmittingtelephone.

In testimony that I claim the foregoing I have hereunto set my hand this 7th day of June, 1895.

ALFRED G. COUSENS.

Witnesses:

AUGUST M. T EsoHoW, AXEL BEEKEN. 

